Precisely deposited Pd on ZnO (002) facets derived from complex reduction strategy for methanol steam reforming

Abstract

Pd/ZnO catalysts are promising for onboard hydrogen production through methanol steam reforming (MSR), but their selectivity still requires improving. In this research, a flower-like spherical ZnO material with mainly exposed (002) facet was prepared through surfactant-assisted hydrothermal method. The surfactant tartaric groups also serve as coordinating groups to adsorb Pd2+ to form a complex, which is further reduced to metallic Pd. By virtue of preferential adsorption of the surfactant on (002) facet, Pd particles are confined to (002) facet. The calcined PdO-ZnO-T-X catalyst shows highly dispersed PdO nanoparticles. Characterization results suggest that strong interaction between ZnO (002) facet and small PdO particles can facilitate complete PdO reduction and PdZn formation, and can effectively retard PdZn decomposition under oxidizing atmosphere. This research discloses structure-performance relationship of Pd/ZnO catalysts and provides a novel strategy for further improving their MSR performance.